Re: Unable to mount degraded RAID5

["Tomáš Hrdina" <thomas.rkh@gmail.com>]

One disk got reallocated sectors in SMART, so i did extended smart test
and it passed. Then I ran scrub and it found nothing. Everything was ok.
After this, it was started another extended smart test, weekly
scheduled, and I thing that sometime during this, disk went offline.

Maybe problem can be, that another disk have smart stat: Reported
Uncorrect on 1.


sudo mount -o ro,degraded,recovery /dev/sda /shares
mount: wrong fs type, bad option, bad superblock on /dev/sda,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.
 
sudo btrfs-show-super -fa /dev/sda and sdb
http://sebsauvage.net/paste/?39c73a3440b2e903#WZnUJXNFPNz/fFuOK3QquVeOWQUopcCl0JabtuYMWew=

sudo btrfs-find-root /dev/sda
warning, device 3 is missing
Couldn't read chunk tree
ERROR: open ctree failed

Thank you
Tomáš

------------------------------------------------------------------------

 *From:* Chris Murphy
 *Sent:*  Monday, July 04, 2016 10:43PM
 *To:* Tomáš Hrdina
*Cc:* Chris Murphy, Btrfs Btrfs
 *Subject:* Re: Unable to mount degraded RAID5

On Mon, Jul 4, 2016 at 1:11 PM, Tomáš Hrdina <thomas.rkh@gmail.com> wrote:
> Result from dmesg:
> http://sebsauvage.net/paste/?4e8e95b5eafbf675#ybToBzZ/WAoRjjugeH6N2YXZKEBlswaNI/J41GBmFYU=

[10849.041749] BTRFS info (device sda): allowing degraded mounts
[10849.041754] BTRFS info (device sda): disk space caching is enabled
[10849.041756] BTRFS: has skinny extents
[10849.090553] BTRFS error (device sda): bad tree block start
10160120763642806272 12678831570944
[10849.090676] BTRFS error (device sda): bad tree block start
10160120763642806272 12678831570944
[10849.090700] BTRFS: failed to read chunk tree on sda
[10849.100153] BTRFS: open_ctree failed


Try 'mount -o ro,degraded,recovery


> 
> sudo btrfs check /dev/sda
> warning, device 3 is missing
> checksum verify failed on 12678831570944 found 3DC57E3E wanted 771D2379
> checksum verify failed on 12678831570944 found 3DC57E3E wanted 771D2379
> bytenr mismatch, want=12678831570944, have=10160133442474442752
> Couldn't read chunk tree
> Couldn't open file system

Want and have are way far apart. If the mount command above still
fails then I'd like to see:

# btrfs-show-super -fa /dev/sda
# btrfs-show-super -fa /dev/sdb

Pretty much look for any discrepancies in generation, root and
chunk_root addresses, both in the main part of the super as well as in
the backups.

# btrfs-find-root /dev/sda

Maybe it's possible to use a different tree to get it mounted. I don't
know what happened but merely a failing device should not either break
checksums or lose the ability to mount the proper tree; but for sure
one of the backups should work.

Have you done a scrub on this file system and do you know if anything
was fixed or if it always found no problem?





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https://www.avast.com/antivirus